Twinsitter
by ZJpotter
Summary: AU. Bill Cipher is left powerless after a failed Weirdmaggedon. Now, stuck in 2004 Bill's revenge plan is targeted at Dipper and Mabel. He's willing to do whatever it takes...even if it means becoming their babysitter.
1. Chapter 1

**Hello! Original Owner alert: This AU's original owner is me. I made it up. Disclaimer: I do not own Gravity Falls or its characters.**

" _It's over Bill." Sixer said_

" _You think you can defeat me!"_

" _We know we can!" Shooting Star said "Now!"_

" _No! No! No!"_

 _The fearamid started to crumble and Bill shrieked._

" _I invoke the ancient power that I may return!"_

 _That was the last thing that happened before the world went white._

The world never seemed so different. There was no screaming people or eye balls in the sky. The sky wasn't orange, but blue. Bill groaned and sat up. There was no sign of Weirdmaggedon anywhere. He looked around. He didn't see any of his fellow demons. He got up…..no that couldn't be right. He wasn't floating.

Bill looked down and saw two human feet (In black shoes) attached to two human legs (in black pants) which were attached to a human body. He had on a yellow brick patterned vest over a white collared shirt and a black bowtie. He had blond hair (With a band that covered an eye patch which covered one of his eyes) and a top hat.

Bill automatically jumped back. He hadn't remembered inhabiting a body and this vessel seemed all too…him. He bent down and picked up a stick. He whacked it against his arm. The pain was less funny this time.

He snapped his fingers. He still wasn't floating. This was a problem.

On his wobbly legs he started walking. Eventually he came out the woodsy area and into the town. It was not Gravity Falls. People walked hand in hand with their children, dogs were on leashes and the birds chirped. There were no familiar faces either.

"Hey you." Bill called to a stranger

The lady smiled at him, "Hello sir."

"What is this place?"

The lady laughed, "Piedmont. You must be new here."

Bill scowled and the lady stopped laughing. Someone did this to him and he was going to find out. He kept walking until the lady's words clicked in. He turned back.

"Did you say Piedmont?"

"Yes." She said

Bill grinned. Pine Tree and Shooting Star were going to be in for a treat.

 **This is only the first chapter but I have a lot planned. I hope you guys liked it! If there's any confusion about what's going on please let me know!**


	2. Chapter 2

Bill sat in the library flipping through the yellow pages. He found that name to be insulting at first. He half-knew how they worked. He used to be an all-powerful demon but that doesn't mean he knew how to use things. Used to be. Bill hadn't figured out how he lost his powers and why he was like this. Maybe he was losing his knowledge too.

He found the P section of the book. In it was an ad.

 _Looking for a babysitting job? If so, please contact 1-510-225-7834 by July 28. – Maggie and Andy Pines_

Bill grinned. He was almost positive that these were the Pines he was looking for. He had been formulating a plan in his head ever since he found out where he was. It was quite simple: find Dipper and Mabel and destroy them so they would never go to Gravity Falls and get in his way. Of course that meant Six-fingers wouldn't bring the rift out the portal, but he would work that out later.

He ripped the page out the book and ran out the library. Only to run back inside to the librarian.

"Hey Lady!" he yelled

"shhh!" the woman shushed him

"Where can you find one of those things?"

The woman gave him a confused look.

"Y'know a payphone?" Bill rolled his eyes  
"A payphone?" The woman gave a short laugh

Bill narrowed his eyes which looked a lot scarier considering only one was visible.

"There's one outside the library sir." She said

He bust out the door and down the stairs to the payphone.

 _50 cents per call._

He groaned. Luckily for him, someone had left money on the ground. He popped it in and dialed the Pines' number.

" _Hello?"_ a female voice answered

"Yello." Bill said "Is this..Maggie Pines?'

" _Yes it is? How may I help you?'_

"I've called about the baby sitting job."

" _Oh! Perfect! Now, I'd love to meet you in person, to y'know discuss things. It'll be like an interview..sorry what's your name?"_

Bill cleared his throat. He debated telling them his name. Then again, they wouldn't be around to remember him.

"Bill Cipher!"

" _Well I should be seeing you. How's tomorrow at 3 sound? At the Lakeview café?"_

"Yeah. Sounds good to me."

" _See you then ."_

Bill grinned. His plan was already working. He was confident about getting the job; if not well he'd find a way to make it happen.

The only problem was where to stay. He had two extra quarters from whomever left money and he was certain no one would just give it to him. Or would they?

 **This chapter's also really short but longer chapters will be soon!**


	3. Chapter 3

**Disclaimer: I still do not own Gravity Falls.**

Bill adjusted his bow tie. Somehow he managed to get a room a local hotel. (There may or may not have been a deal involved). He also managed to get the babysitting job. He considered the interview a success.

 _"_ _So, Mr. Cipher, any experience with kids?" Maggie Pines asked_

 _"_ _Tons of it!" Bill said (surely turning them into a throne of agony counted.)_

He turned away from the mirror, grabbed his bag, and went out the hotel to catch the Piedmont bus. From inside the bus Bill realized how much he missed floating everywhere. His feet were seriously starting to hurt. Pine Tree and Shooting Star were going to have to pay for what they did. He'd make sure they'd never get to go to Gravity Falls.

When he got off he walked a little bit to the Pines' house. It was small with two stories almost resembling a log cabin. He rang the doorbell and Maggie Pines answered. She was slightly shorter than Bill with brown curly hair. She had suitcases in her hands.

" !" she grinned "It's so good to see you."

A man rushed by taking the luggage from her. He was Bill's height with brown hair as well. It must be Andy.

"Call me Bill." He said

"Well, Bill, I apologize for our rushing." Maggie said "We're about to leave for our trip. Speaking of, Dipper and Mabel are just so excited to meet you!"

"Oh me too." Bill grinned

"In the kitchen, I left important numbers and food information. I also left any other instructions we didn't discuss. I assume you remember where you will be staying as well as the kids. If not I left everything in a nice little note." Maggie said all in one breath

Outside, Andy honked the car.

"Your kids will be in good hands Mrs. Pines." Bill tipped his hat

"Well then, I've already said goodbye..." Maggie looked over her shoulder "They're in the living room. Goodbye Bill. See you in a week."

She left and locked the door. Bill tried to keep his grin in control as he walked into the living room. In front of the TV, on the floor sat Pine Tree and Shooting Star. Pine Tree was wearing a red shirt with shorts. His eyes were glued to the TV and he had no hat. Shooting Star was coloring in a coloring book clutching a unicorn toy. Her hair was in pigtails and she wore an oversized dress. Bills stepped in front of the TV. He towered over the small kids. They looked up at him.

Pine Tree inched closer to his twin.

"Name's Bill Cipher."

"That's a funny name." Shooting Star said

"Mabel!" her twin gasped

"I'm your new babysitter." Bill grinned

Pine Tree narrowed his eyes suspicious, but Shooting Star jumped up.

"Weally? I'm Mabel!" she held up her toy "This is Princess Wuvacorn! Dippy he's gonna pway wit us!"

"Yeah. Sure kid." Bill said making a mental note to refer to her as Mabel and her twin as Dipper

"Are you gonna watch TV with us?" Dipper asked

Bill shrugged.

"Games?"

Bill shrugged.

"Toys?" Dipper asked

Bill shrugged. Dipper crossed his arms. For a four year old he sure was defensive. He leaned over to his twin and she sat down. He whispered something to her and she frowned and shook her head. Dipper whispered to her again. Bill groaned.

"You two hungry or something?" Bill asked

"Yes!" Mabel shot up again "Can we go get sprinkles?"

"You mean ice cream?"

Mabel shook her head.

Bill did not want am even more hyper Mabel, "I think your Mom left some food."

The twins rushed into the kitchen ahead of him. By the time Bill got there the Twins were already sitting in booster seated chairs.

Bill wandered to the fridge and opened it. A note stuck to a tub of chicken nuggets.

 _These are for their lunch. Please serve with ketchup located in the shelf below._ _J_ _\- Maggie_

Bill took it out. He eyed the microwave. He sort of knew how to use one. Being a demon before meant he didn't need to know. He placed the nuggets on a paper plate and grabbed the ketchup. He struggled to get it out.

"You pat it." Mabel said from her chair

He ignored Mabel's advice and struggled some more before getting a blob of ketchup on the nuggets. Then he popped it in the microwave. There were way too many buttons.

Dipper sighed, "I'm Hungry."

Mabel nodded and the two chanted how hungry they were.

"Shut it!" Bill snapped and pressed a button

Mabel giggled. Soon the plates of warm, ketchupy, nuggets was in front of the twins. Mabel picked up a soggy one.

"Yucky." She said and she had been known to make gross things

Dipper nodded.

"It can't be that bad.' Bill tried one and immediately stared hacking

"I stand corrected." Bill said as the twins laughed

 **Thanks for the reviews! I hope you enjoyed this chapter!**


	4. Chapter 4

**Disclaimer: No owning of Gravity Falls here.**

It was night and Bill still couldn't get the taste of those chicken nuggets out of his mouth. He just let the two eat ice cream with extra sprinkles. He saw now that it was a bad idea.

"Wee!" Mabel bounced on her bed with pigtails flying

Bill managed to get her to put on her nightgown and that took a while. Her bed was next to Dipper's. The contrast was certainly noticeable. Dipper's side of the room was neat, with toy trucks, other toys and some books. Mabel's was covered in pink, stuffed animals, crayons, coloring books, and dress up costumes. She bounced over to his bed scaring him out of his block building.

"Mabel!" he said staring at the fallen blocks of

Bill groaned, "Alright you two, in bed now."

"Will you read us…"Dipper went to the edge of his bed and picked up a book "This?"

The title read _The Purple Dragon._

"No." Bill said

"Pwease!" Mabel said hopping over to her bed "Mommy always reads to us."

Bill nearly snapped there. He really wanted to get this over with and obliterate them already, but then Maggie had to check up on her babies. He'd do it tomorrow first chance he got.

"No." he said "There's no way I'm reading about some dumb dragon!"

"He isn't dumb!" Dipper crossed his arms

"I've seen some real dragons kid." Bill said "He ain't one!"

"You've seen a dragon?" Mabel and Dipper asked

Bill smacked his hand on his forehead, "If I read you the dumb story will you go to sleep?"

"Yes sir!" the two said

…

"Good morning!"

Bills shrieked. The two laughing Pines kids were on the floor laughing. It took a second for Bill to figure out what was going on. He was in his assigned room looking a pajama clad kids. Oh, that's right.

"You two. Out. Now."

"But we want breakfast." Mabel said

"Now, or you'll never get breakfast again!"

"Meanie!" Mabel stuck her tongue out at him as the two left

Bill sat up fully. He'd been a babysitter for approximately 24 hours and he wanted it to end. It was going to. Except, as he rummaged through his bag he found a flaw.

He had no clue why he was human (His floating and powers hadn't returned) and how to get back to his triangle self and present day. It had something to do with that prophecy. Unfortunately visiting Ford now would create a serious dent in the space time continuum not to mention he already had a metal plate in his head.

….

Once Bill was dressed he found them in the kitchen.

"Mommy called." Mabel said "She said we can go to eat."

"At the…the….dinner." Dipper said

"You mean the diner?"

Dipper nodded grinning. Bill was not in the mood to take those two anywhere but to be honest he didn't want soggy chicken nuggets again.

"Alright let's go."

"Onwards Aoshima!" Mabel cheered

"What?"

"It's Mabel talk." Dipper said following his sister out the kitchen

 **I wanted to give a reason for that in the show besides Smile Dip. (Even though it's a person's name) I can update quicker now since summer vacation is here! Yay! Hope you enjoyed this chapter!**


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